FIG 2.

Hydrocarbon biodegradation within 0.1 and 1% (vol/vol) diesel (A, C, E, and G)- and crude oil (B, D, F, and H)-amended microcosms with nutrient stimulation or without (ambient). (A and B) Concentration of hydrocarbon compound groups at day 0 (pre-treatment) and after 71 days of incubation at 4°C. Hydrocarbon concentrations in diesel were obtained by normalizing compound peak areas against 1,3+3,9+2,10+3,10-dimethylphenanthrene, and in crude oil by normalizing against 17α(H),21β(H)-hopane. (C and D) Biodegradation conveyed as losses of measured n-alkanes (C₁₂-C₂₅) and PAHs from pre-treatment levels. (E to H) CO₂ production (E and F) determined by GC is plotted as the difference between hydrocarbon-amended and -unamended microcosms and was used to estimate rates of CO₂ production associated with hydrocarbon biodegradation (G and H) (CO₂ concentrations for unamended controls are shown in Fig. S1). Error bars represent standard errors of triplicate microcosms of the same treatment.